The message was a direct shot at his newest rival, Gov. Rick Perry of Texas, who said this week that climate change was ''a scientific theory that has not been proved'' and called evolution ''just a theory.''

For Mr. Huntsman, the message was also part of a broader strategy to stake out a part of the Republican primary field that is not so crowded: the moderate part.

''Mr. Huntsman is going to position himself as he always has, as a truth-teller,'' said Tim Miller, a spokesman for his campaign. ''He doesn't believe the party can be an antiscience party.''

But Mr. Huntsman's efforts to stand apart from the pack only go so far. At the debate in Iowa last week, the candidates were asked how many would oppose a plan in which spending cuts outweighed revenue increases by 10 to 1.

All hands went up, including Mr. Huntsman's.

That could have been a missed opportunity for Mr. Huntsman to draw a distinction between himself and his Republican rivals on a national stage -- and attract more attention than a single Twitter message.

But Mr. Miller said that Mr. Huntsman did not believe that the federal government needed any revenue increases right now. Mr. Miller said Mr. Huntsman did, however, distinguish himself by being the only candidate to approve of the debt deal reached in Washington.

''He doesn't think tax increases right now are smart,'' Mr. Miller said. But he added that Mr. Huntsman was eager to stand out on issues when he can.

''I'm sure we'll have more,'' he promised.

And sure enough, a few minutes later, Mr. Huntsman sent another Twitter message:

I wonder if a tweet where I admit how much I like Captain Beefheart will make the followers skyrocket even more! http://t.co/1yqlwYAThu Aug 18 19:45:09 via Twitter for iPhoneJon Huntsman
JonHuntsman

This is a more complete version of the story than the one that appeared in print.